Dr Ronald Stiffler SEC technology

[gyulasun]

Hi Itsu,

Very, very nice result with the 200 Vpp tank circuit voltage !   

I can agree with your reasonings for L3 forming a series circuit with the Alu backplate when viewing them from the generator output. This can also explain the reduction of the generator output voltage, also this loading is what takes the energy from the xtal oscillator. 

Regarding the transistor, can you think of a 100 V fast switching bipolar power transistor you may have in one of your drawers? IF you do not have such at hand, what component suppliers can you reach at your place to order from? I could help select from the choices in stock offered by them. You may PM if you wish of course.

Thanks,
Gyula


EDIT  if you have mouser.com in your country, here are some good transistor types, with very low collector-emitter saturation voltages and higher than 100 V collector voltage ratings:https://mouser.com/ProductDetail/Diodes-Incorporated/ZTX855STZ?qs=sGAEpiMZZMshyDBzk1%2fWizF0eVyYE44Z2nyOhAR0%252bHE%3d

https://mouser.com/ProductDetail/ON-Semiconductor/2SC4027S-E?qs=sGAEpiMZZMshyDBzk1%2fWiwdH0KqkRU51WtddJ3XM6TA%3d

https://mouser.com/ProductDetail/ON-Semiconductor/2SD1815S-E?qs=sGAEpiMZZMshyDBzk1%2fWiwdH0KqkRU513QpD3tszHKs=
 
If the links do not work for somebody, the transistor types are included in the links (ZTX855STZ, 2SC4027S-E, 2SD1815S-E).

[NickZ]

  Speaking of transistors...  I've been working on making a crystal oscillator, as well.  I'm using the 2SC5200 transistor,  an unknown value choke with some 2.5ohms resistance, a 100k ohm resistor, a 22pf cap, and a 100nf cap before the home made L3.  They are all used parts from my junk pile. Which is why they look so old and rusty. Oh, and also a 12.000MHz crystal.

  The problem that I'm having is that although I get the 12v input through all the filters and chokes, I only get 0.5v at the transistor base, between the emitter and base. I don't know if I should be measuring it another way. But, there does not seam to be enough voltage at the transistor base to properly switch.
 
The input is from severall lithium ion batteries,  there's 12v at the collector/emitter, but the transistor is not switching.   
Any ideas are welcome.                                     
   BTW:  I do have several of the 1815 and 945 transistors, if I can't make the 5200 turn on, but no 2222.
   
   PS:  Itsu:  Great to see you here, and showing some very nice results, as well.                                                                                                                                                                                               NickZ

[Slider2732]

Neither the 1815 or 945 are rubbish for this...they work.
Most especially the C1815 if GR variety, quite excellent.

You say 100ohms ? the one across the crystal ?
That's far too low it does need to be approx 100K.

If no joy, physically tapping the L3 may start it up if it doesn't start on its own.
I would advise putting an LED from Emitter to Base in reverse (positive of the LED to batt negative). That way, when the LED is on, the circuit is running.

[mikrovolt]

The crystal oscillator can be filtered to improve the wave shape.
A low distortion sine wave has better harmonics.
The theoretical LC values can be found for any impedance using the web page calculator listed above.

[itsu]

Gyula,

i tried a BF869 which i had, but it did not oscillate somehow also a TIP122 with same result.
I will try to locate one of your mentioned transistors in my pile of circuitboards or else
order some, they look just what i need.

The switching off / on of the oscillator i see, seems to be due to it flipping into a 3th harmonics
(40MHz @ low amplitude) oscillation with the 5K trimmer pot at a certain point (low ohms value).

The reason for running at the 12V (and blowing the transistor) is that at that voltage the oscillator
seems to work best showing a nice sine wave etc.   
Lowering the voltage (keeping the transistor alive) seems to distort the signal it can produce.



Nick,

try to run the oscillator without the L3 coil attached first.
The L3 and leds causes strange influence on the oscillator, making it to stall often.


Itsu